Flame Synthesis of Nanocrystalline Yttria Stabilized Zirconia Powders from Aqueous Precursors

Abstract

Flame reactors are considered to be one of the promising and versatile equipment for making nanocrystalline ceramic powders. Flame synthesis of nanocrystalline yttria stabilized zirconia (YSZ) was carried out using zirconium oxy-nitrate and yttrium nitrate as precursors. The yttria (Y2O3) content was systematically varied from 8 mol% to 12 mol.% in zirconia in order to stabilize either partially or fully the monoclinic crystal structure. Precursor solutions of 1(M) concentration were prepared by dissolving in de-ionised water. X-ray diffraction of the as-synthesized powders confirmed that the cubic phase had been stabilized, except in the case of 8 mol% YSZ prepared from the precursor solution. All the powders were nanocrystalline in nature with the crystallite size increasing from 45 nm to 62 nm with increasing yttria content. Scanning electron microscopy revealed the powder characteristics to be typical of an aerosol based processing technique. The specific surface area, measured by nitrogen adsorption, was 14-15 m2g-1. By pressureless sintering technique, more than 99% of the theoretical density was achieved. Abbreviations: YSZ: Yttria Stabilized Zirconia; SOFC: Solid Oxide Fuel Cell; XRD: X-Ray Diffraction; BET: BrunauerEmmett-Teller.